March/April 1996
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March/April 1996 |
by Frank Bevacqua
If we think of human health studies as lenses of a microscope, what can we see when we look through them? What do we know after we've looked at the slides we have? And what do current research efforts hope to add to our knowledge?
A recently-released report to the U.S. Congress by the U.S. Environmental Protection Agency (U.S. EPA) addresses these questions by describing the current Great Lakes research program of the U.S. Agency for Toxic Substances and Disease Registry (ATSDR) and earlier health studies.
Studies in the 1970s and 1980s found that people who ate Great Lakes fish had significantly higher levels of contaminants in their blood than those who did not. In addition, children of mothers who ate Great Lakes fish showed small, but measurable difference in birth weight, head circumference, muscle reflexes and recognition and memory functions. These differences seemed to relate to exposure the child received in the womb to certain long-lasting toxic substances, such as PCBs.
These findings were of concern because a variety of health problems also appeared in the offspring of Great Lakes wildlife that were exposed to the same persistent toxic substances. Policymakers were concerned that, in addition to cancer risks, these substances posed health risks to unborn children. But there were many questions about the nature and extent of the risks that could not be answered.
For one thing, there were problems comparing the results of different human health studies. A number found links between health effects in babies and the amount of fish their mothers had eaten. But the mothers in various studies had eaten different amounts of fish and the health effects found in the children were not identical.
In the meantime, techniques for identifying and measuring the contaminants in the mothers' and children's blood were improving significantly. So by our analogy, the researchers were not only looking at different slides through their microscopes, they were looking through different lenses as well.
In 1990, the U.S. Congress passed amendments to the Federal Water Pollution Control Act that called for a more comprehensive assessment of health effects of water pollutants in the Great Lakes basin. Under the act the U.S. EPA transferred a total of $8 million to ATSDR for the first three years of research. ATSDR developed a research program that includes grants for eight epidemiologic studies, a study to develop more sensitive methods to detect contaminants in human tissues and fluids, and an interlaboratory quality assurance and control program.
Epidemiologic studies compare the health of populations exposed to different levels of contaminants. In combination with other analytical tools, they usually provide the most convincing evidence of human health effects. They can also provide the understanding needed to target control actions such as health advisories, regulations or medical intervention. But they are costly and time consuming. Six of the eight ATSDR-funded epidemiologic studies build on six existing human health studies.
In addition to providing a more comprehensive understanding of human health effects, the ATSDR research program also plans to increase public awareness of health issues related to Great Lakes pollution and work with health officials at all levels to address health issues as the study findings become available over the next year.
A portion of The Effects of Great Lakes Contaminants on Human Health: Report to Congress is available via Internet at ((insert URL address)). To obtain the full report, contact Diane Dennis-Flagler, U.S. Environmental Protection Agency (G-9J), 77 West Jackson Boulevard, Chicago, IL 60604-3590; telephone (312)886-4012; fax (312)353-2018.
Sommaire
Si les études sur la santé humaine étaient les lentilles d'un microscope, que révéleraient-elles?
Un rapport récemment publié par le Congrès des États-Unis, intitulé The Effects of Great Lakes Contaminants on Human Health, se penche sur cette question en décrivant l'actuel programme de recherche sur les Grands Lacs de l'Agency for Toxic Substances and Disease Registry (ATSDR) des États-Unis, ainsi que des études antérieures sur la santé.
Revised: 28 February 1997
Maintained by Kevin McGunagle,
mcgunaglek@ijc.wincom.net